Modelling and performance evaluation of a soot cyclone separator

Abstract

This mini-dissertation reports on the performance of a cyclone separator used to remove excess soot that is typically formed during the production of pebble fuel for High Temperature Gas-cooled Reactors. A chemical vapour deposition process is used to manufacture TRISO-coated fuel particles and during this process soot is formed that needs to be removed. This removal process uses cyclone separators as pre-filters and a bag filter as the final means of preventing unwanted particles from being introduced into the atmosphere. An important requirement of the cyclone separator is the need for a safe geometry design. This implies that the containment of enriched-uranium fuel particles can under no circumstances result in a criticality situation. An advantage of this safe geometry design is that it eliminates the use of expensive gamma detectors within the cyclone separator. In this mini-dissertation, the performance of a new safe geometry cyclone separator design to be used in the removal of soot in the manufacturing of TRISO-coated particles was investigated via theoretical modelling. Various models for predicting the performance of cyclone separators are in existence. These were examined and the best-suited model for the task at hand was selected. The model as described by Li and Wang appeared to be the most applicable and useful, given the available information, such as the cyclone geometries and particle characteristics. Li and Wang’s model, as with many of the other models in the literature, were developed to calculate the collection efficiency. This model was first benchmarked with empirical data obtained from the current cyclone separator used in the production of coated particles at the Pebble Bed Modular Reactor (PBMR) Advance Coater Facility (ACF) situated at Pelindaba in South Africa. The calibrated model was then used to predict the collection efficiencies of three newly designed cyclone separators. The results obtained from the model predicted an increase in collection efficiency for all the newly designed cyclone separators when compared to the existing units. Therefore, this project found that any of the newly designed cyclones should serve as a good alternative to the current cyclone separator.